Toggle latch



L. R. POE

TOGGLE LATCH 2 Sheets-Sheet 1 Filed June l, 1960 SJP INVENTOR LLOYD R. POE

ATTORNE ug. 28, 1962 R, POE 3,051,520

TOGGLE LATCH Filed June l, 1960 2 Sheets-Sheet 2 (12 2?l l ITHLZI E? /H M l/I2 i l @f f INVENTOR LLOYD R. POE

ATTORNE 3,951,529 TOGGLE LATCH Lloyd R. Poe, Los Angeles, Calif., assigner to Hartwell Corporation, a corporation of California Filed .lune 1, 1966, Ser. No. 33,145 4 Claims. (Cl. 292-223) This invention relates to improvements in toggle latches particularly adapted for flush mounting in the surfaces of smooth panels, such as access and inspection doors.

The principal feature of this invention is the provision of a latch bolt which, even though absolutely prevented from being opened by loads acting on the bolt, has a range of travel when the bolt is in the latched position. This permits the use of only one size of latch in installations where keepers or jams against which the latch bolt bears may be of different thicknesses or tolerances. Moreover, no special means are required for iinal adjustment of the latch after it is installed, when the latch is so constructed that within the range of travel of the bolt, it positively secures a door or other closure against vibration and partial opening.

Another feature of this invention is the provision of a toggle latch which can be opened easily without regard to loads carried by the latch and at the same time provide a simple latch mechanism which will be reliable under varying load conditions and under loads which are heavy in relation to the design strength of the latch, A particular advantage of latch mechanisms according to this invention is that, as bolt loading is increased, resultant forces transmitted throughout the mechanism tend to increase the force with which the mechanism is held in the latched position.

According to my invention a latch bolt and a manually operable lever are pivotably mounted on a support plate. The latch bolt and lever are independently arranged on fixed axes for limited rotation between latching and retracted positions. The iixed axes are arranged parallel to each other at opposite ends of the support.

lThe latch bolt has a keeper bearing surface which projects outwardly of and generally parallel to the support in the latching position. Also, in the latching position the lever is disposed iiush with the surface of a door or movable panel on which the latch mechanism may be mounted.

In the retracted position the latch bolt is withdrawn to a position under the support and the lever projects above the panel or door surface. In this position the lever can be used as a handle for manually opening such a door or panel.

The mechanism of the invention further comprises a connecting link which is pivotahly mounted at its opposite ends on the latch bolt and lever. The ends of the connecting link are arranged on movable axes, that is, axes which can move relative to the xed axes above mentioned.

The outer end of the link is arranged on a first movable axis in the latch bolt. This iirst movable axis is disposed in the end of the latch bolt generally below and oifset from the latch bolt iixed axis. The other end of the link is arranged on a second movable axis lin the lever.

ln the latching position, the second movable axis is disposed parallel to but below a plane defined by the lever iixed axis and the first movable axis. In this position, bearing loads which may be applied to the keeper bearing surface of the latch bolt tend to increase the force with which the lever is held in the latching position. For positive action and to insure that the second movable axis will assume and not be vibrated from this position, a torsion spring is provided to bias the lever end of the link.

ln the retracted position, the second movable axis lies parallel to but above a plane deiined by the lever fixed axis and the first movable axis. The torsion spring provided 3,951,520 Patented Aug. 28, 1962 also provides positive action when the latch is being retracted. As soon as the second movable axis crosses a plane as defined above, the force of the spring causes the second movable axis to snap to the upper position described. In this upper position, the spring also holds the mechanism against stops provided to limit the retracting movement.

At and about the first movable axis in the latch bolt, the latch bolt of this invention has oblong holes. These holesA are larger than the diameter of a shaft or pin which may be used at this axis for an axle. With these oblong holes, a range of motion `is provided for the latch bolt when the bolt is in the latching position. To prevent chattering and loose tits, a second torsion spring is also provided in the latch bolt. This spring is used to bias the upper bearing surface of the bolt against the keeper of a given installation.

With such a range of motion, the latch of this invention becomes self-accommodating to keepers or door jams which may be of various thicknesses. This range of motion is small in any given latch model and will not cause upset of the toggle action at the second movable axis in the latching position. This limited latch bolt mo-tion does, however, permit one size of latch to be readily installed for use on doors where keepers or door jams, otherwise similar, are of different thicknesses or tolerances.

Other features and advantages of this invention Will be apparent from the following description. In the course of the description reference is made to the accompanying drawings, in which:

FIG. l is a plan view of the flush-mounted latch of this invention in place in the latched position in an inspection door such as may be found in aircraft.

FIG. 2 is a view of the underside of the panel and latch of'FIG. l;

FIG. 3 is a cross section view of the latch of the invention taken along line 3 3 of FIG. 2; and,

FIG. 4 is a cross section View of the latch of the invention in the retracted position.

In FIGS. l land 2 the latch of this invention 10 is shown attached to a door 11 in panel 12. Projecting through an opening in the door and flush with the surface thereof is a button 15 which is accessible from the outside of the door for manual actuation.

lAs may be seen more clearly in FIGS. 3 and 4, button 15 is part of lever 14.y Lever 14 also comprises a mount 16. Mount 16 has two parallel arms each of which has portions in acute angular relationship to one another. One end of each of the arms is attached to the button 15. The other ends are pivotably affixed to the -underside `of latch Support 17 at a first xed axis 18. Lever 14 rotates through a limited arc about the yaxis 18 in response to manual operation of lbutton 15 for moving latch 10 lbetween latching and retracted positions.

To accommodate the Ilever 14, support 17 has an opening 27 through which the arms of mount 16 project. Support 17 also has a well 20 recessed in its upper side to accommodate the limited rotation of button 15.

At the other end of support 17, also on the underside thereof a second xed axis 21 is arranged to pivotably Support a latch bolt 22. Latch bolt 22 has a flat keeper bearing surface 23 which projects beyond support 17 sufb- `stantially parallel thereto, in the latched position (note FIG. 3). As shown, the second iixed axis 21 is removed from the bearing surface 23 at the inner end of latch bolt 22.

Link 24 connects lever 14 and latch Ibolt 22 so that bolt 2,2 can be moved when the lever is operated lbetween latching and retracted positions. The link 24 is rotatably axed at its ends to axes which are movable relative 3 movable axis 25 also in the inner end of the latch bolt 22. First movable axis 25 is offset in bolt 22 below a line connecting the keeper bearing surface 23 and the second fixed axis 21.

The other end of link 24 is arranged on a second movable axis 26 in the arms of mount 16. The second movable axis 26 is at the junctures of the described acute angular portions of the arms in mount 16.

IIn the latching position as shown in FIG. 3, it can be seen that the second movable axis 26 lies below a plane defined by the first axes, i.e., the first fixed -axis 18 and the first movable axis 25. With second movable axis 26 below this plane, bearing loads applied to the keeper bearing surface 23 of latch bolt 22 produce oompression in link 24 and a downward force component acting through the second movable axis 26 and the upper arms of lever 14. Such a force component causes button of lever 14 to bear against support 17 so that maintenance of the latching position is assured, as long as, of course, the forces do not exceed the structural limits of materials used.

In the retracted position as shown in FIG. 4, the second movable axis 26 lies above a plane defined by the first axes 18 and 25. This position is obtained by manually depressing the end of button 15 which is cantilevered over well 20. Stops for this retracted position can be easily provided by designing well so that the end of button 15 bears against the inner wall of the Well. Stops can also be provided by the edge of opening 27 so that the arms of mount 16 'bear against the edge in the retracted position.

As shown in FIG. 4, the opposite end of button 15 projects above support 17. This opposite button end is sufficiently large to provide a convenient handle or grip when rthe button is disposed above the Surface of a door on which the latch is used. The button of lever 14 may then be grasped when the latch is retracted to pull the door, such as door 11 in rFIG. l, open.

'As described, button 15 seats firmly on support 17 in the latched position. This action provides a seal around the edges of opening 27 in support 17. In this way the latch provided by this invention is dust and splash proof. lf additional sealing protection is desired, a vgasket may also be installed around opening 27.

It should be understood that the several axes of rotation described above can be provided -in different ways depending on the structural shapes used in the latch components. They are conveniently provided in the embodiment described by holes drilled through the interconnected components. These holes are aligned concentric with the desired axis in each case and pins are inserted therethrou-gh to maintain such alignment and provide an axle at each of the axes. The ends of the pins are spread or peened -to keep them from falling out.

T'o insure positive toggle action at the second movable axis 26, a torsion spring 28 is used. This spring 28 has a coil portion which is disposed around la pin -at the first movable axis 25. Spring 28 also has end portions one of which bears against a pin at the second fixed axis 21 and the other against a pin at the second movable axis 26. The spring 28 is in compression so that its end portions exert opposing forces which act through axes 21 and 26.

The force exerted through the second movable axis 26 biases link 24 and Ilever 14 so that the second movable axis 26 is lhel-d below the plane defined by first axes and 18 when the mechanism is in the latched position. This biasing force insures that changes in air pressure on the ou-ter surfaces of door 11 and button 15 and that operating vibrations will not cause the latch bolt 23 to retract.

When lever 14 is actuated to move latch bolt 22 to the retracted position, force exerted through the second movable axis 26 causes the mechanism to snap open yas soon as axis 26 crosses a plane defined by first axes 25 4 and 18. The biasing force exerted through axis 26 vthen bolds the second movable axis above that plane with the mechanism engaging the stops provided.

Oblong lholes 29 are provided in latch bol-t 22 about the pin at the first movable axis 25. With oblong holes 29, the latch bolt 22 has a range of movement in the latched position. This range is suiciently small so that the locking action at the second movable axis 26, above described, is not disturbed when the mechanism is in the latched position.

However, with the oblong holes 29, the fiat keeper bearing surface 23 can accommodate keepers or door jams of various thicknesses. Often such keepers or jams are manufactured to equal norminal dimensions but, within tolerance limits of, for example, .06 inch, actual thicknesses will vary. The latches of this invention can be readily installed, notwithstanding such variations.

The deflection range provided for latch bolt 22 is small relative to its overall length. It can therefore be said that the keeper bearing surface 23 is disposed generally parallel to -support 17 lwhen in the latched position. In this parallel position, keeper bearing surface 23 can move parallel to itself to adjust to the thickness variations. This movement in a specific latch model can be, as mentioned, .06- inch.

To prevent loose fitting and chattering, a second torsion spring 30 .is provided at latch bolt 22. This spring 30 has two coils disposed around a pin at the second fixed axis 21. The coils are connected by a loop 19 which is disposed against the coil of torsion spring 28. Spring 30 also has end portions which project under keeper bearing surface 23. Spring 30 being stressed, exerts forces which act through first movable axis 25 and which act upward against said keeper bearing surface 23. This spring load causes bolt 22 to bear against the object it engages at all times when the mechanism is in the latching position.

This arrangement is important because time and attendant expense are not required for final installation adjustments or perhaps remachining or parts substitution. Models of this latch can be readily standardized for general rather than .specific applications. Such standardiza- -tion reduces procurement times as well as unit costs because these latches are therefore adaptable to mass production techniques and inventory stocking.

Having thus described my invention, I wish it understood that many details discussed above are illustrative. Accordingly, the scope of my invention is defined in the following claims.

I claim:

l. In a flush type toggle latch having a support structure, a level pivotably mounted at a first fixed axis near one end of said support, a latch bolt rotatably supported at a second fixed -axis remote from said first fixed axis, said latch bolt having a keeper bearing surface, said second fixed axis being at one end of said bolt remote from said bearing surface, said bolt being rotatable about said second fixed axis between latching and retracted positions, a connecting link rotatably aixed at its ends to said lever and to said latch bolt, one end of said link being afixed to said bolt at a first movable axis, said first movable axis being at said latch bolt one end and offset from a line connecting said keeper bearing surface and said second fixed axis, the other end of said link being affixed to said lever at a second movable axis, said first vaxes defining a plane, said second movable axis being below said plane in said latchng position and above the same in said retracted position, and a torsion spring having a coil portion encompassing said first movable axis and end portions connected to said second axes, the improvement which comprises oblong passages in said latch bolt one end, said passages being disposed at and about said first movable axis to accommodate limited swinging movement of said bolt when said second movable axis is below said plane.

2. The toggle latch combination of claim l yand in which .said support has a well type depression in its upper surface, said lever has a button type portion exposed above said support for manual actuation which button portion is supported, in said latching position, with one end thereof over said depression, said depression being of a depth and Width to accommodate said button one end when the latch is in said retracted position.

3. The toggle latch combination of claim 2 and in which said button one end resides in contact with an inner Wall of said depression to limit swinging movement of said lever in `said retracted position.

4. The toggle latch combination of claim 2 and which a second torsion spring is disposed in said latch bolt,

5 latch bolt bearing surface.

References Cited in the le of this patent UNiTED STATES PATENTS Larson Apr. 2, 1946 2,621,952 Gander Dec. 16, 1952 2,927,812 Smith et al. Mar. 8, 1960 

